<html>
<head><meta charset="utf-8"><title>meeting 2021-02-09 · wg-traits · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/index.html">wg-traits</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html">meeting 2021-02-09</a></h3>

<hr>

<base href="https://rust-lang.zulipchat.com">

<head><link href="https://rust-lang.github.io/zulip_archive/style.css" rel="stylesheet"></head>

<a name="225755525"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225755525" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225755525">(Feb 09 2021 at 20:52)</a>:</h4>
<p>Anyone have any preference for meeting topic today?</p>



<a name="225755563"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225755563" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225755563">(Feb 09 2021 at 20:52)</a>:</h4>
<p>Between last meeting and today, I did triage for named type aliases: <a href="https://hackmd.io/W4khQJyIQdy_ezT9xUdgQg">https://hackmd.io/W4khQJyIQdy_ezT9xUdgQg</a></p>



<a name="225755663"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225755663" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225755663">(Feb 09 2021 at 20:53)</a>:</h4>
<p>Also, <a href="https://github.com/rust-lang/rust/issues/79554">#79554</a> has landed, which fixed a bunch of GAT issues</p>



<a name="225755899"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225755899" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Santiago Pastorino <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225755899">(Feb 09 2021 at 20:55)</a>:</h4>
<p><span class="user-mention" data-user-id="232957">@Jack Huey</span> can I be added to the zulip group?</p>



<a name="225755975"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225755975" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225755975">(Feb 09 2021 at 20:56)</a>:</h4>
<p>Sure but I don't know how to do that</p>



<a name="225755989"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225755989" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Santiago Pastorino <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225755989">(Feb 09 2021 at 20:56)</a>:</h4>
<p>oh I guess I should be able because I'm Zulip admin</p>



<a name="225756046"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756046" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Santiago Pastorino <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756046">(Feb 09 2021 at 20:57)</a>:</h4>
<p>done :)</p>



<a name="225756108"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756108" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Santiago Pastorino <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756108">(Feb 09 2021 at 20:57)</a>:</h4>
<p>btw, I'm still trying to organize myself a bit before taking some work, hope I'm able to start doing some stuff before the end of this week</p>



<a name="225756115"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756115" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> detrumi <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756115">(Feb 09 2021 at 20:57)</a>:</h4>
<p>I guess we can just talk through ongoing work if we don't have a special meeting topic</p>



<a name="225756248"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756248" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756248">(Feb 09 2021 at 20:58)</a>:</h4>
<p>That works</p>



<a name="225756270"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756270" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756270">(Feb 09 2021 at 20:58)</a>:</h4>
<p>Not sure if maybe <span class="user-mention" data-user-id="116009">@nikomatsakis</span> had something in mind</p>



<a name="225756386"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756386" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756386">(Feb 09 2021 at 20:59)</a>:</h4>
<p><span class="user-mention" data-user-id="125131">@detrumi</span> I <em>still</em> haven't gotten to your Chalk PR :/</p>



<a name="225756397"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756397" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756397">(Feb 09 2021 at 21:00)</a>:</h4>
<p>I feel bad</p>



<a name="225756478"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756478" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756478">(Feb 09 2021 at 21:00)</a>:</h4>
<p>Okay <span class="user-group-mention" data-user-group-id="692">@WG-traits</span> meeting time :)</p>



<a name="225756507"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756507" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756507">(Feb 09 2021 at 21:00)</a>:</h4>
<p>wave</p>



<a name="225756513"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756513" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756513">(Feb 09 2021 at 21:00)</a>:</h4>
<p>I didn't have a <em>particular</em> agenda</p>



<a name="225756521"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756521" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> detrumi <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756521">(Feb 09 2021 at 21:00)</a>:</h4>
<p>Heh, I guess not having time is just part of becoming a compiler team member</p>



<a name="225756529"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756529" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756529">(Feb 09 2021 at 21:00)</a>:</h4>
<p>I started <span class="user-mention" data-user-id="232957">@Jack Huey</span> reading over your binder PR</p>



<a name="225756531"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756531" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756531">(Feb 09 2021 at 21:00)</a>:</h4>
<p>and I got a bit overwhelmed :)</p>



<a name="225756547"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756547" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756547">(Feb 09 2021 at 21:00)</a>:</h4>
<p>i am however</p>



<a name="225756565"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756565" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756565">(Feb 09 2021 at 21:00)</a>:</h4>
<p>slowly slowly revising my schedule, and I have for example new blocks of time to focus on things</p>



<a name="225756585"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756585" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756585">(Feb 09 2021 at 21:01)</a>:</h4>
<p>so I'd like people to start giving me things to review :P</p>



<a name="225756626"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756626" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756626">(Feb 09 2021 at 21:01)</a>:</h4>
<p>Niko, if it helps, we can schedule some time to go through it together and talk things through</p>



<a name="225756639"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756639" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756639">(Feb 09 2021 at 21:01)</a>:</h4>
<p>I was going to suggest that</p>



<a name="225756648"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756648" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756648">(Feb 09 2021 at 21:01)</a>:</h4>
<p>I think that for a huge PR like this it makes a lot of sense</p>



<a name="225756712"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756712" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Santiago Pastorino <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756712">(Feb 09 2021 at 21:02)</a>:</h4>
<p><span class="user-mention" data-user-id="232957">@Jack Huey</span> is <a class="stream-topic" data-stream-id="144729" href="/#narrow/stream/144729-wg-traits/topic/rustc.20binder.20refactor">#wg-traits &gt; rustc binder refactor</a> still up or what's the PR that Niko is going to review? :)</p>



<a name="225756771"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756771" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756771">(Feb 09 2021 at 21:02)</a>:</h4>
<p>the other thing I was starting to do was to break out the <a href="https://hackmd.io/5kCE2T6sTDijhqMx8kaikw">path to async functions in traits</a> into milestones</p>



<a name="225756783"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756783" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756783">(Feb 09 2021 at 21:02)</a>:</h4>
<p>but <span class="user-mention" data-user-id="232957">@Jack Huey</span> that coverage of type alias impl trait is super useful</p>



<a name="225756793"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756793" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756793">(Feb 09 2021 at 21:02)</a>:</h4>
<p><span class="user-mention" data-user-id="116009">@nikomatsakis</span> let's set up a time after the meeting :)</p>



<a name="225756801"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756801" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756801">(Feb 09 2021 at 21:02)</a>:</h4>
<p>actually, i'm going to make a hackmd team for the traits group I think :)</p>



<a name="225756822"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756822" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756822">(Feb 09 2021 at 21:02)</a>:</h4>
<p>so we can start adding things into it to make them easier to find</p>



<a name="225756868"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756868" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756868">(Feb 09 2021 at 21:02)</a>:</h4>
<p><span class="user-mention" data-user-id="116266">@Santiago Pastorino</span> so, the PR as a whole is ready, but specifically the handling of hrtbs and associated type bounds need some design/impl work :)</p>



<a name="225756990"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225756990" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225756990">(Feb 09 2021 at 21:03)</a>:</h4>
<p>From what I can tell, GATs are "close"</p>



<a name="225757007"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757007" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757007">(Feb 09 2021 at 21:03)</a>:</h4>
<p>but named type aliases have a bit of work do to</p>



<a name="225757061"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757061" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757061">(Feb 09 2021 at 21:04)</a>:</h4>
<p>So</p>



<a name="225757068"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757068" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757068">(Feb 09 2021 at 21:04)</a>:</h4>
<p>(GATs triage doc for reference: <a href="https://hackmd.io/uxoObhSxSRijNmfmGkId0g">https://hackmd.io/uxoObhSxSRijNmfmGkId0g</a>)</p>



<a name="225757074"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757074" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757074">(Feb 09 2021 at 21:04)</a>:</h4>
<p>I'm not sure if you saw the "slice 0" concept</p>



<a name="225757082"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757082" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757082">(Feb 09 2021 at 21:04)</a>:</h4>
<p>but I think that's key :)</p>



<a name="225757094"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757094" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757094">(Feb 09 2021 at 21:04)</a>:</h4>
<p>I did not</p>



<a name="225757103"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757103" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757103">(Feb 09 2021 at 21:04)</a>:</h4>
<p>created: <a href="https://hackmd.io/team/rust-wg-traits/">https://hackmd.io/team/rust-wg-traits/</a></p>



<a name="225757157"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757157" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757157">(Feb 09 2021 at 21:04)</a>:</h4>
<p>maybe start transferring hackmds in there...</p>



<a name="225757190"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757190" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757190">(Feb 09 2021 at 21:05)</a>:</h4>
<p>I added the folks i saw in this meeting so far</p>



<a name="225757194"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757194" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757194">(Feb 09 2021 at 21:05)</a>:</h4>
<p>Shoot, I have so many</p>



<a name="225757197"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757197" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> detrumi <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757197">(Feb 09 2021 at 21:05)</a>:</h4>
<p>Ooh, nice</p>



<a name="225757202"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757202" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757202">(Feb 09 2021 at 21:05)</a>:</h4>
<p>no rush</p>



<a name="225757232"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757232" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757232">(Feb 09 2021 at 21:05)</a>:</h4>
<p>I didn't even know that was a thing. That's awesome</p>



<a name="225757273"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757273" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757273">(Feb 09 2021 at 21:05)</a>:</h4>
<p>Niko can you summarize slice 0 in a couple sentences?</p>



<a name="225757324"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757324" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757324">(Feb 09 2021 at 21:06)</a>:</h4>
<p>yeah, it's also covered in <a href="https://hackmd.io/nzqSIjdHTFW3-IT3ZWRjow">this doc</a> in more detail</p>



<a name="225757357"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757357" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757357">(Feb 09 2021 at 21:06)</a>:</h4>
<p>the basic idea is that if we focus on a particular subset of impl Trait, the behavior is (we believe) fairly close to what we want</p>



<a name="225757361"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757361" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757361">(Feb 09 2021 at 21:06)</a>:</h4>
<p>that subset specifically is:</p>



<a name="225757392"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757392" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757392">(Feb 09 2021 at 21:06)</a>:</h4>
<div class="codehilite" data-code-language="Rust"><pre><span></span><code><span class="k">type</span> <span class="nc">Foo</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">impl</span><span class="w"> </span><span class="n">Trait</span><span class="p">;</span><span class="w">  </span><span class="c1">// either at module or impl level</span>
</code></pre></div>
<p>where <code>Foo</code> is only used in the return type of functions</p>



<a name="225757464"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757464" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757464">(Feb 09 2021 at 21:07)</a>:</h4>
<p>there are some notes and a <a href="https://hackmd.io/nzqSIjdHTFW3-IT3ZWRjow#Work-plan-and-time-estimates">work plan</a> in that doc as well</p>



<a name="225757475"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757475" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757475">(Feb 09 2021 at 21:07)</a>:</h4>
<p>this is i think the first milestone to be shooting for</p>



<a name="225757488"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757488" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757488">(Feb 09 2021 at 21:07)</a>:</h4>
<p>you know what i'm sensing ;)</p>



<a name="225757499"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757499" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757499">(Feb 09 2021 at 21:07)</a>:</h4>
<p>skill tree!</p>



<a name="225757611"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757611" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757611">(Feb 09 2021 at 21:08)</a>:</h4>
<p>I &lt;3 the skill tree</p>



<a name="225757650"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757650" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757650">(Feb 09 2021 at 21:08)</a>:</h4>
<p>I'm trying to decide how to start "sketching' it</p>



<a name="225757669"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757669" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757669">(Feb 09 2021 at 21:09)</a>:</h4>
<p>I guess, my question is what <em>isn't</em> covered by slice 0</p>



<a name="225757682"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757682" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757682">(Feb 09 2021 at 21:09)</a>:</h4>
<p>(not sure how much of that is in the doc)</p>



<a name="225757684"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757684" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757684">(Feb 09 2021 at 21:09)</a>:</h4>
<p>some examples:</p>



<a name="225757700"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757700" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> detrumi <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757700">(Feb 09 2021 at 21:09)</a>:</h4>
<p>Notably, parameter position</p>



<a name="225757708"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757708" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757708">(Feb 09 2021 at 21:09)</a>:</h4>
<div class="codehilite" data-code-language="Rust"><pre><span></span><code><span class="k">type</span> <span class="nc">Foo</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">impl</span><span class="w"> </span><span class="n">Trait</span><span class="p">;</span><span class="w"></span>

<span class="k">fn</span> <span class="nf">some_function</span><span class="p">(</span><span class="n">f</span>: <span class="nc">Foo</span><span class="p">)</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="o">..</span><span class="w"> </span><span class="p">}</span><span class="w"></span>
</code></pre></div>



<a name="225757718"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757718" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757718">(Feb 09 2021 at 21:09)</a>:</h4>
<p>or</p>



<a name="225757727"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757727" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757727">(Feb 09 2021 at 21:09)</a>:</h4>
<div class="codehilite" data-code-language="Rust"><pre><span></span><code><span class="kd">let</span><span class="w"> </span><span class="n">x</span>: <span class="nc">Foo</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">..</span><span class="p">.;</span><span class="w"></span>
</code></pre></div>



<a name="225757731"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757731" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757731">(Feb 09 2021 at 21:09)</a>:</h4>
<p>or</p>



<a name="225757740"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757740" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757740">(Feb 09 2021 at 21:09)</a>:</h4>
<div class="codehilite" data-code-language="Rust"><pre><span></span><code><span class="kd">let</span><span class="w"> </span><span class="n">x</span>: <span class="nc">impl</span><span class="w"> </span><span class="n">Trait</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="o">..</span><span class="p">.;</span><span class="w"></span>
</code></pre></div>



<a name="225757793"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757793" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757793">(Feb 09 2021 at 21:10)</a>:</h4>
<p>there is another doc that preceded that "slice 0" doc</p>



<a name="225757802"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757802" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757802">(Feb 09 2021 at 21:10)</a>:</h4>
<p>let me see if I can find it</p>



<a name="225757810"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757810" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757810">(Feb 09 2021 at 21:10)</a>:</h4>
<p>it had some more notes</p>



<a name="225757829"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757829" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757829">(Feb 09 2021 at 21:10)</a>:</h4>
<p><code>let x: Foo</code> is allowed outside of the defining scope though, right?</p>



<a name="225757832"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757832" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757832">(Feb 09 2021 at 21:10)</a>:</h4>
<p><a href="https://hackmd.io/4dafnCiTSiOZJy_3u4ju0A">https://hackmd.io/4dafnCiTSiOZJy_3u4ju0A</a></p>



<a name="225757880"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757880" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757880">(Feb 09 2021 at 21:10)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116118">Matthew Jasper</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225757829">said</a>:</p>
<blockquote>
<p><code>let x: Foo</code> is allowed outside of the defining scope though, right?</p>
</blockquote>
<p>yes</p>



<a name="225757896"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757896" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757896">(Feb 09 2021 at 21:10)</a>:</h4>
<p>Neat</p>



<a name="225757940"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757940" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757940">(Feb 09 2021 at 21:11)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116009">nikomatsakis</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225757832">said</a>:</p>
<blockquote>
<p><a href="https://hackmd.io/4dafnCiTSiOZJy_3u4ju0A">https://hackmd.io/4dafnCiTSiOZJy_3u4ju0A</a></p>
</blockquote>
<p>this one defines a 'slice 1"</p>



<a name="225757959"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757959" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757959">(Feb 09 2021 at 21:11)</a>:</h4>
<p>and some of the thorny questions</p>



<a name="225757973"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225757973" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225757973">(Feb 09 2021 at 21:11)</a>:</h4>
<p>which probably intersects some of the issues you triaged</p>



<a name="225758007"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758007" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758007">(Feb 09 2021 at 21:11)</a>:</h4>
<p><a href="https://hackmd.io/WUQLxHdDRFm2jw1SOXm4Ug">skill tree sketch document</a></p>



<a name="225758034"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758034" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758034">(Feb 09 2021 at 21:11)</a>:</h4>
<p>side note that hackmd actually has a lot of ways to categorize stuff</p>



<a name="225758050"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758050" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758050">(Feb 09 2021 at 21:11)</a>:</h4>
<p>e.g., adding hashtags and things</p>



<a name="225758053"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758053" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758053">(Feb 09 2021 at 21:11)</a>:</h4>
<p>that we don't use at all, but probably should</p>



<a name="225758063"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758063" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> detrumi <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758063">(Feb 09 2021 at 21:12)</a>:</h4>
<p><del>that links to the slice 1 doc?</del></p>



<a name="225758082"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758082" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758082">(Feb 09 2021 at 21:12)</a>:</h4>
<p>given how many crazy docs we have</p>



<a name="225758128"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758128" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758128">(Feb 09 2021 at 21:12)</a>:</h4>
<p><span class="user-mention silent" data-user-id="125131">detrumi</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225758063">said</a>:</p>
<blockquote>
<p>that links to the slice 1 doc?</p>
</blockquote>
<p>fixed</p>



<a name="225758279"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758279" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758279">(Feb 09 2021 at 21:13)</a>:</h4>
<p>So, a quick detour</p>



<a name="225758283"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758283" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758283">(Feb 09 2021 at 21:13)</a>:</h4>
<p>For GATs</p>



<a name="225758318"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758318" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758318">(Feb 09 2021 at 21:13)</a>:</h4>
<p>How are we feeling about stabilizing lifetimes-only vs all</p>



<a name="225758337"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758337" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758337">(Feb 09 2021 at 21:13)</a>:</h4>
<p>I was just pondering that</p>



<a name="225758412"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758412" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758412">(Feb 09 2021 at 21:14)</a>:</h4>
<p>I don't know if there are that many more open questions around types vs. lifetimes.</p>



<a name="225758422"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758422" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758422">(Feb 09 2021 at 21:14)</a>:</h4>
<p>What are the <em>risks</em></p>



<a name="225758449"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758449" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758449">(Feb 09 2021 at 21:14)</a>:</h4>
<p>I guess not having <code>for&lt;T&gt;</code> syntax limits them a bit.</p>



<a name="225758456"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758456" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758456">(Feb 09 2021 at 21:14)</a>:</h4>
<p>right, I was about to say there are very few issues that apply only to non-lifetimes</p>



<a name="225758470"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758470" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758470">(Feb 09 2021 at 21:14)</a>:</h4>
<p>I still feel a certain measure of uncertainty because i wish we had worked out the whole polonius-chalk strategy better</p>



<a name="225758473"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758473" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> detrumi <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758473">(Feb 09 2021 at 21:14)</a>:</h4>
<p>Harder to find potential problems in time</p>



<a name="225758514"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758514" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758514">(Feb 09 2021 at 21:14)</a>:</h4>
<p>but I don't want to block on that</p>



<a name="225758559"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758559" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758559">(Feb 09 2021 at 21:15)</a>:</h4>
<p>and I kind of feel like there's already a ton of pre-existing behavior we have to contend with</p>



<a name="225758574"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758574" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758574">(Feb 09 2021 at 21:15)</a>:</h4>
<p>GATs with Trait objects are further from being usable than types type-GATs imo.</p>



<a name="225758584"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758584" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758584">(Feb 09 2021 at 21:15)</a>:</h4>
<p>There are 3 filed issues currently, 2 are duplicate and have a PR. And the 3rd isn't GAT-specific</p>



<a name="225758593"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758593" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758593">(Feb 09 2021 at 21:15)</a>:</h4>
<p>this is a good point</p>



<a name="225758622"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758622" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758622">(Feb 09 2021 at 21:15)</a>:</h4>
<p>3 filed issues for what?</p>



<a name="225758650"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758650" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758650">(Feb 09 2021 at 21:15)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116009">nikomatsakis</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225758470">said</a>:</p>
<blockquote>
<p>I still feel a certain measure of uncertainty because i wish we had worked out the whole polonius-chalk strategy better</p>
</blockquote>
<p>Maybe we can schedule a meeting to go over this?</p>



<a name="225758678"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758678" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758678">(Feb 09 2021 at 21:15)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116009">nikomatsakis</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225758622">said</a>:</p>
<blockquote>
<p>3 filed issues for what?</p>
</blockquote>
<p>non-lifetime GATs</p>



<a name="225758768"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758768" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758768">(Feb 09 2021 at 21:16)</a>:</h4>
<p>But I'm sure there are plenty of things that just haven't been tested well</p>



<a name="225758795"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758795" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758795">(Feb 09 2021 at 21:16)</a>:</h4>
<p>I see</p>



<a name="225758802"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758802" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758802">(Feb 09 2021 at 21:16)</a>:</h4>
<p>let's talk about trait objets for a bit</p>



<a name="225758803"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758803" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758803">(Feb 09 2021 at 21:16)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116118">Matthew Jasper</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225758574">said</a>:</p>
<blockquote>
<p>GATs with Trait objects are further from being usable than types type-GATs imo.</p>
</blockquote>
<p>Can you elaborate on this?</p>



<a name="225758885"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758885" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758885">(Feb 09 2021 at 21:17)</a>:</h4>
<p>There is a bug with object safety currently that I've fixed locally. But maybe I'm missing a more general problem</p>



<a name="225758918"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758918" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758918">(Feb 09 2021 at 21:17)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116009">nikomatsakis</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225758802">said</a>:</p>
<blockquote>
<p>let's talk about trait objets for a bit</p>
</blockquote>
<p>oops, ninja'd</p>



<a name="225758934"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225758934" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225758934">(Feb 09 2021 at 21:17)</a>:</h4>
<p>there's usability problems I think</p>



<a name="225759000"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759000" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759000">(Feb 09 2021 at 21:18)</a>:</h4>
<p>also i saw some notes about <code>for</code> syntax that i found confusing</p>



<a name="225759048"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759048" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759048">(Feb 09 2021 at 21:18)</a>:</h4>
<p>I think I saw an example like <code>for&lt;'a&gt; dyn Iterable&lt;Iter&lt;'a&gt; = ...&gt;</code> ?</p>



<a name="225759062"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759062" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759062">(Feb 09 2021 at 21:18)</a>:</h4>
<p>that makes no sense to me at all :)</p>



<a name="225759071"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759071" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759071">(Feb 09 2021 at 21:18)</a>:</h4>
<p>Relevant issue: <a href="https://github.com/rust-lang/rust/issues/81823">#81823</a></p>



<a name="225759090"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759090" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759090">(Feb 09 2021 at 21:18)</a>:</h4>
<p>Where?</p>



<a name="225759108"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759108" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759108">(Feb 09 2021 at 21:18)</a>:</h4>
<p>I must have missed that</p>



<a name="225759114"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759114" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759114">(Feb 09 2021 at 21:19)</a>:</h4>
<p>you wrote it!</p>



<a name="225759129"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759129" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759129">(Feb 09 2021 at 21:19)</a>:</h4>
<p>:O</p>



<a name="225759141"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759141" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759141">(Feb 09 2021 at 21:19)</a>:</h4>
<p>at least I thought you did</p>



<a name="225759171"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759171" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759171">(Feb 09 2021 at 21:19)</a>:</h4>
<p>This issue: <a href="https://github.com/rust-lang/rust/blob/185de5f41a64e1b790524d5873dc1f7e368f64ab/compiler/rustc_trait_selection/src/traits/select/confirmation.rs#L462">https://github.com/rust-lang/rust/blob/185de5f41a64e1b790524d5873dc1f7e368f64ab/compiler/rustc_trait_selection/src/traits/select/confirmation.rs#L462</a></p>



<a name="225759175"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759175" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759175">(Feb 09 2021 at 21:19)</a>:</h4>
<p>but I see that in this issue <span class="user-mention" data-user-id="116118">@Matthew Jasper</span> wrote this <code>for</code> syntax</p>



<a name="225759209"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759209" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759209">(Feb 09 2021 at 21:19)</a>:</h4>
<p>it seems confusing to me -- I expect the <code>'a</code> in <code>Iter&lt;'a&gt;</code> to be a <em>binder</em></p>



<a name="225759246"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759246" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759246">(Feb 09 2021 at 21:20)</a>:</h4>
<p>that would shadow the <code>'a</code> in <code>for&lt;'a&gt;</code></p>



<a name="225759314"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759314" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759314">(Feb 09 2021 at 21:20)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116009">nikomatsakis</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225759114">said</a>:</p>
<blockquote>
<p>you wrote it!</p>
</blockquote>
<p>/me frantically searches for this</p>



<a name="225759324"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759324" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759324">(Feb 09 2021 at 21:20)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116009">nikomatsakis</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225759114">said</a>:</p>
<blockquote>
<p>you wrote it!</p>
</blockquote>
<p><span class="user-mention" data-user-id="232957">@Jack Huey</span> <a href="https://github.com/rust-lang/rust/issues/44265#issuecomment-775423925">here</a>:</p>
<blockquote>
<p>To begin, a lot of blocking issues related to specifying GATs in trait paths (e.g. <code>for&lt;'a&gt; T: Foo&lt;Y&lt;'a&gt; = u32&gt;</code>) have now been "resolved" with <a href="https://github.com/rust-lang/rust/issues/79554">#79554</a>. However, this isn't <em>completely</em> resolved, since we haven't completely decided whether you need that <code>for&lt;'a&gt;</code> or if you should be able to (or must) elide that. As long as we decide you don't <em>have</em> to omit it, allowing the elision in the future is probably a backwards-compatible change.</p>
</blockquote>



<a name="225759368"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759368" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> detrumi <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759368">(Feb 09 2021 at 21:20)</a>:</h4>
<p>(from <a href="https://github.com/rust-lang/rust/issues/44265#issuecomment-775423925">https://github.com/rust-lang/rust/issues/44265#issuecomment-775423925</a>)</p>



<a name="225759370"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759370" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759370">(Feb 09 2021 at 21:20)</a>:</h4>
<p>hmm</p>



<a name="225759380"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759380" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759380">(Feb 09 2021 at 21:21)</a>:</h4>
<p>I guess that's not about <code>dyn</code></p>



<a name="225759391"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759391" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759391">(Feb 09 2021 at 21:21)</a>:</h4>
<p>maybe I misunderstood</p>



<a name="225759398"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759398" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759398">(Feb 09 2021 at 21:21)</a>:</h4>
<p>i still don't quite understand it either way though :)</p>



<a name="225759407"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759407" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759407">(Feb 09 2021 at 21:21)</a>:</h4>
<p>(for the same reason)</p>



<a name="225759440"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759440" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759440">(Feb 09 2021 at 21:21)</a>:</h4>
<p>Oops did I make a mistake</p>



<a name="225759482"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759482" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759482">(Feb 09 2021 at 21:22)</a>:</h4>
<p>I actually expect that code to be an error</p>



<a name="225759533"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759533" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759533">(Feb 09 2021 at 21:22)</a>:</h4>
<p>since we generally forbid shadowing lifetimes</p>



<a name="225759597"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759597" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759597">(Feb 09 2021 at 21:22)</a>:</h4>
<p>It's not a binder, it's plausibly useful to use a non-fully generic arg in bounds, e.g. <code>PtrFamily&lt;Ptr&lt;i32&gt; = Rc&lt;i32&gt;&gt;</code>, so it's not a definition.</p>



<a name="225759603"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759603" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759603">(Feb 09 2021 at 21:22)</a>:</h4>
<p>I'm not sure we <em>should</em> forbid that, but we do</p>



<a name="225759623"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759623" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759623">(Feb 09 2021 at 21:22)</a>:</h4>
<p>hmm</p>



<a name="225759641"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759641" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759641">(Feb 09 2021 at 21:22)</a>:</h4>
<p>I guess it's true that you could do that</p>



<a name="225759668"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759668" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759668">(Feb 09 2021 at 21:22)</a>:</h4>
<p>but there needs to be the option of a binder</p>



<a name="225759683"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759683" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759683">(Feb 09 2021 at 21:22)</a>:</h4>
<p>and <code>for&lt;'a&gt; T: Foo&lt;...&gt;</code> is not the right place for it</p>



<a name="225759698"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759698" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759698">(Feb 09 2021 at 21:23)</a>:</h4>
<p>I mean, it's ok</p>



<a name="225759723"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759723" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759723">(Feb 09 2021 at 21:23)</a>:</h4>
<p>Well</p>



<a name="225759768"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759768" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759768">(Feb 09 2021 at 21:23)</a>:</h4>
<p>it's just not the only option</p>



<a name="225759778"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759778" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759778">(Feb 09 2021 at 21:23)</a>:</h4>
<p>I think this was the design question</p>



<a name="225759789"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759789" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759789">(Feb 09 2021 at 21:23)</a>:</h4>
<p><code>T: Foo&lt;for&lt;'a&gt; Y&lt;'a&gt; = ...&gt;</code></p>



<a name="225759794"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759794" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759794">(Feb 09 2021 at 21:23)</a>:</h4>
<p>dear god</p>



<a name="225759796"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759796" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759796">(Feb 09 2021 at 21:23)</a>:</h4>
<p>oh how do you "define" that <code>'a</code></p>



<a name="225759801"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759801" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759801">(Feb 09 2021 at 21:23)</a>:</h4>
<p>:)</p>



<a name="225759852"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759852" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759852">(Feb 09 2021 at 21:23)</a>:</h4>
<p>I do feel like there's some ergonomic issues to resolve with GATs...</p>



<a name="225759867"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225759867" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225759867">(Feb 09 2021 at 21:23)</a>:</h4>
<p>I think there was some previous discussion here</p>



<a name="225760025"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760025" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760025">(Feb 09 2021 at 21:25)</a>:</h4>
<p>I'd like to read it</p>



<a name="225760127"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760127" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760127">(Feb 09 2021 at 21:25)</a>:</h4>
<p>So, <a href="https://github.com/rust-lang/rust/issues/79266">#79266</a> is a start</p>



<a name="225760165"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760165" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760165">(Feb 09 2021 at 21:25)</a>:</h4>
<p>still trying to find more</p>



<a name="225760219"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760219" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760219">(Feb 09 2021 at 21:26)</a>:</h4>
<p>maybe in some of the resolved conversations?</p>



<a name="225760225"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760225" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760225">(Feb 09 2021 at 21:26)</a>:</h4>
<p>I don't see much there</p>



<a name="225760252"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760252" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760252">(Feb 09 2021 at 21:26)</a>:</h4>
<p>sigh</p>



<a name="225760260"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760260" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760260">(Feb 09 2021 at 21:26)</a>:</h4>
<p>I've sometimes wished that we did declarations differently</p>



<a name="225760286"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760286" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760286">(Feb 09 2021 at 21:26)</a>:</h4>
<p>specifically I wish that we did</p>



<a name="225760303"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760303" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760303">(Feb 09 2021 at 21:26)</a>:</h4>
<p>I think there's some older conversations somewhere</p>



<a name="225760316"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760316" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760316">(Feb 09 2021 at 21:26)</a>:</h4>
<p>I'll look later</p>



<a name="225760325"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760325" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760325">(Feb 09 2021 at 21:26)</a>:</h4>
<p><code>struct Foo&lt;type T&gt; { ... }</code> -- using the keyword means "ths is a declaration'</p>



<a name="225760328"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760328" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760328">(Feb 09 2021 at 21:26)</a>:</h4>
<p>so that you could do</p>



<a name="225760336"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760336" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760336">(Feb 09 2021 at 21:27)</a>:</h4>
<p><code>impl Foo&lt;type T&gt; { .. }</code></p>



<a name="225760365"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760365" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760365">(Feb 09 2021 at 21:27)</a>:</h4>
<p>this is relevant because then you could do</p>



<a name="225760432"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760432" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760432">(Feb 09 2021 at 21:27)</a>:</h4>
<p><code>T: Iterable&lt;Iter&lt;lifetime a&gt; = a&gt;</code></p>



<a name="225760448"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760448" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760448">(Feb 09 2021 at 21:27)</a>:</h4>
<p>except i would not want that keyword</p>



<a name="225760463"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760463" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760463">(Feb 09 2021 at 21:27)</a>:</h4>
<p>/me considers whether to push for this</p>



<a name="225760475"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760475" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760475">(Feb 09 2021 at 21:27)</a>:</h4>
<p>Eh, I feel like that would get verbose quickly</p>



<a name="225760480"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760480" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760480">(Feb 09 2021 at 21:27)</a>:</h4>
<p>that'd be an edition change if I ever saw one :)</p>



<a name="225760493"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760493" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760493">(Feb 09 2021 at 21:27)</a>:</h4>
<p>I think it'd be less verbose</p>



<a name="225760515"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760515" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760515">(Feb 09 2021 at 21:28)</a>:</h4>
<p>well, maybe not</p>



<a name="225760549"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760549" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760549">(Feb 09 2021 at 21:28)</a>:</h4>
<p>anyway, no matter</p>



<a name="225760561"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760561" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760561">(Feb 09 2021 at 21:28)</a>:</h4>
<p>a similar principle applies</p>



<a name="225760565"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760565" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760565">(Feb 09 2021 at 21:28)</a>:</h4>
<p>e.g.,</p>



<a name="225760576"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760576" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760576">(Feb 09 2021 at 21:28)</a>:</h4>
<p><code>T: Iterable&lt;Iter&lt;for 'a&gt; = &amp;'a u32&gt;</code></p>



<a name="225760584"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760584" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760584">(Feb 09 2021 at 21:28)</a>:</h4>
<p>oh hmm</p>



<a name="225760652"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760652" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> detrumi <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760652">(Feb 09 2021 at 21:29)</a>:</h4>
<p><code>&lt;for 'a&gt;</code> would hinder introducing multiple lifetimes though</p>



<a name="225760678"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760678" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760678">(Feb 09 2021 at 21:29)</a>:</h4>
<p>why</p>



<a name="225760689"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760689" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> detrumi <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760689">(Feb 09 2021 at 21:29)</a>:</h4>
<p>as opposed to <code>for&lt;'a,'b&gt;</code></p>



<a name="225760693"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760693" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760693">(Feb 09 2021 at 21:29)</a>:</h4>
<p>ah, you would do</p>



<a name="225760717"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760717" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760717">(Feb 09 2021 at 21:29)</a>:</h4>
<p><code>T: Iterable&lt;Iter&lt;for 'a, for 'b&gt; = ... &gt;</code></p>



<a name="225760725"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760725" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760725">(Feb 09 2021 at 21:29)</a>:</h4>
<p>anyway, I'm just trying to think outside the box a bit</p>



<a name="225760744"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760744" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760744">(Feb 09 2021 at 21:29)</a>:</h4>
<p>this is probably not the right venue for this brainstorming</p>



<a name="225760805"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760805" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760805">(Feb 09 2021 at 21:30)</a>:</h4>
<p>but I would want to think about these sorts of issues before we stabilized</p>



<a name="225760820"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760820" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760820">(Feb 09 2021 at 21:30)</a>:</h4>
<p>(side note that <code>impl MyStruct&lt;for T&gt; { ... }</code> would work too :)</p>



<a name="225760848"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760848" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760848">(Feb 09 2021 at 21:30)</a>:</h4>
<p>I think <code>for T</code> syntax is not bad :)</p>



<a name="225760899"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760899" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760899">(Feb 09 2021 at 21:31)</a>:</h4>
<p>But unsure what more it gets you</p>



<a name="225760929"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760929" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760929">(Feb 09 2021 at 21:31)</a>:</h4>
<p>other than in trait paths</p>



<a name="225760967"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760967" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760967">(Feb 09 2021 at 21:31)</a>:</h4>
<p>mostly I thnk that <code>T: Iterable&lt;for&lt;'a&gt; Iter&lt;'a&gt; = u32&gt;</code> is a nonstarter</p>



<a name="225760978"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760978" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760978">(Feb 09 2021 at 21:31)</a>:</h4>
<p>I can barely parse that here, on zulip</p>



<a name="225760992"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225760992" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225760992">(Feb 09 2021 at 21:31)</a>:</h4>
<p>imagine a bunch of code like that...</p>



<a name="225761056"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761056" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761056">(Feb 09 2021 at 21:32)</a>:</h4>
<p>in general I don't feel the <code>for&lt;'a&gt;</code> syntax has scaled especially well</p>



<a name="225761064"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761064" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761064">(Feb 09 2021 at 21:32)</a>:</h4>
<p>Of course, I forgot there was a separate issue <a href="https://github.com/rust-lang/rust/issues/67510">#67510</a></p>



<a name="225761129"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761129" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761129">(Feb 09 2021 at 21:32)</a>:</h4>
<p><span class="user-mention silent" data-user-id="232957">Jack Huey</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225760929">said</a>:</p>
<blockquote>
<p>other than in trait paths</p>
</blockquote>
<p>if you're talking about my impl example, I think it would make things more concise, but we can discuss it later</p>



<a name="225761149"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761149" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761149">(Feb 09 2021 at 21:32)</a>:</h4>
<p>the other option would be <code>let</code></p>



<a name="225761166"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761166" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761166">(Feb 09 2021 at 21:32)</a>:</h4>
<p>anyway</p>



<a name="225761172"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761172" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761172">(Feb 09 2021 at 21:32)</a>:</h4>
<p>And see <a href="https://github.com/rust-lang/rust/issues/67510#issuecomment-699144813">https://github.com/rust-lang/rust/issues/67510#issuecomment-699144813</a></p>



<a name="225761224"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761224" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761224">(Feb 09 2021 at 21:33)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116009">nikomatsakis</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225761129">said</a>:</p>
<blockquote>
<p><span class="user-mention silent" data-user-id="232957">Jack Huey</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225760929">said</a>:</p>
<blockquote>
<p>other than in trait paths</p>
</blockquote>
<p>if you're talking about my impl example, I think it would make things more concise, but we can discuss it later</p>
</blockquote>
<p>let's discuss later for sure :)</p>



<a name="225761238"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761238" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761238">(Feb 09 2021 at 21:33)</a>:</h4>
<p>ok so "GAT syntax" is a big thin to be resolved</p>



<a name="225761309"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761309" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761309">(Feb 09 2021 at 21:33)</a>:</h4>
<p>Hopefully sooner, rather than later</p>



<a name="225761374"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761374" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761374">(Feb 09 2021 at 21:34)</a>:</h4>
<p>I would hate to move things forward a lot then decided to completely change the syntax</p>



<a name="225761451"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761451" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761451">(Feb 09 2021 at 21:34)</a>:</h4>
<p>I'm kind of into some proposal like this, but I would want to do it universally</p>



<a name="225761497"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761497" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761497">(Feb 09 2021 at 21:35)</a>:</h4>
<p>e.g., instead of <code>for&lt;'a&gt; dyn Foo&lt;'a&gt;</code> you could do <code>dyn Foo&lt;for 'a&gt;</code></p>



<a name="225761500"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761500" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761500">(Feb 09 2021 at 21:35)</a>:</h4>
<p>So, Niko, you <em>don't</em> like the <code>for&lt;'a&gt; T: Foo&lt;Bar&lt;'a&gt; = Baz&lt;'a&gt;&gt;</code> syntax</p>



<a name="225761522"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761522" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761522">(Feb 09 2021 at 21:35)</a>:</h4>
<p>well</p>



<a name="225761558"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761558" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761558">(Feb 09 2021 at 21:35)</a>:</h4>
<p>so, <span class="user-mention" data-user-id="116118">@Matthew Jasper</span> convinced me that the <code>'a</code> in <code>bar&lt;'a&gt;</code> is not necessarily a binder site</p>



<a name="225761585"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761585" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761585">(Feb 09 2021 at 21:35)</a>:</h4>
<p>correct</p>



<a name="225761600"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761600" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761600">(Feb 09 2021 at 21:35)</a>:</h4>
<p>it's not that I don't like that syntax -- but it's hard to read, and I'm not sure if we all agree on what it means :)</p>



<a name="225761666"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761666" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761666">(Feb 09 2021 at 21:36)</a>:</h4>
<p>I mean, theoretically you could just do <code>T: Foo&lt;Bar&lt;'a&gt; = Baz&lt;'a&gt;&gt;</code></p>



<a name="225761679"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761679" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761679">(Feb 09 2021 at 21:36)</a>:</h4>
<p>I forget if I saw why we didn't do that</p>



<a name="225761715"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761715" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761715">(Feb 09 2021 at 21:36)</a>:</h4>
<p>presumably you can do that, if <code>'a</code> is bound somewhere else?</p>



<a name="225761753"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761753" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> detrumi <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761753">(Feb 09 2021 at 21:37)</a>:</h4>
<p>Do you mean the <code>for</code> is implicit there?</p>



<a name="225761892"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761892" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761892">(Feb 09 2021 at 21:38)</a>:</h4>
<p><span class="user-mention" data-user-id="116009">@nikomatsakis</span>, yes, we shouldn't be able to shadow <code>'a</code></p>



<a name="225761932"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761932" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761932">(Feb 09 2021 at 21:38)</a>:</h4>
<p>And <span class="user-mention" data-user-id="125131">@detrumi</span>, I think the concern here is it doesn't <em>really</em> make sense as a "for"</p>



<a name="225761943"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761943" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761943">(Feb 09 2021 at 21:38)</a>:</h4>
<p>since it isn't <em>binding</em></p>



<a name="225761974"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225761974" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225761974">(Feb 09 2021 at 21:38)</a>:</h4>
<p>(please someone correct me if I'm wrong)</p>



<a name="225762015"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762015" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> detrumi <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762015">(Feb 09 2021 at 21:39)</a>:</h4>
<p>Ah, I was assuming it was a binding. But I could be wrong there</p>



<a name="225762133"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762133" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762133">(Feb 09 2021 at 21:40)</a>:</h4>
<p><code>'a</code> is free in <code>T: Foo&lt;Bar&lt;'a&gt; = Baz&lt;'a&gt;&gt;</code> and would have to have already been defined.</p>



<a name="225762237"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762237" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762237">(Feb 09 2021 at 21:41)</a>:</h4>
<p>Well <span class="user-mention" data-user-id="116118">@Matthew Jasper</span> I think the proposal I'm making here is that by putting <code>Bar&lt;'a&gt;</code> you <em>are</em> defining it</p>



<a name="225762281"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762281" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762281">(Feb 09 2021 at 21:41)</a>:</h4>
<p>Then what's the syntax for using an existing lifetime?</p>



<a name="225762348"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762348" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762348">(Feb 09 2021 at 21:42)</a>:</h4>
<p>What would using an existing lifetime there mean?</p>



<a name="225762375"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762375" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762375">(Feb 09 2021 at 21:42)</a>:</h4>
<p>(I think I'm confused about that)</p>



<a name="225762397"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762397" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762397">(Feb 09 2021 at 21:42)</a>:</h4>
<p>you could do it</p>



<a name="225762417"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762417" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762417">(Feb 09 2021 at 21:42)</a>:</h4>
<p>if you think of chalk</p>



<a name="225762454"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762454" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762454">(Feb 09 2021 at 21:43)</a>:</h4>
<p>That <code>&lt;T as Foo&gt;::Bar&lt;'a&gt; == Baz&lt;'a&gt;</code> and for other lifetimes the result isn't specified.</p>



<a name="225762468"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762468" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762468">(Feb 09 2021 at 21:43)</a>:</h4>
<p>it would basically be <code>ProjectionEq(&lt;T as Iterable&gt;::Iter&lt;'a&gt; = &amp;'a u32)</code></p>



<a name="225762498"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762498" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762498">(Feb 09 2021 at 21:43)</a>:</h4>
<p>analogous to how you can do <code>T: Trait&lt;'a, Foo = u32&gt;</code></p>



<a name="225762509"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762509" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762509">(Feb 09 2021 at 21:44)</a>:</h4>
<p>which would be <code>ProjectionEq(&lt;T as Trait&lt;'a&gt;&gt;::Foo = u32)</code></p>



<a name="225762599"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762599" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762599">(Feb 09 2021 at 21:44)</a>:</h4>
<p>Well...but...why would you need a different lifetime in <code>Iter&lt;'a&gt;</code></p>



<a name="225762609"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762609" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762609">(Feb 09 2021 at 21:44)</a>:</h4>
<p>well</p>



<a name="225762621"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762621" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762621">(Feb 09 2021 at 21:45)</a>:</h4>
<p>you'd basically be saying</p>



<a name="225762629"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762629" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762629">(Feb 09 2021 at 21:45)</a>:</h4>
<p>"the iterator for this specific lifetime"</p>



<a name="225762639"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762639" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762639">(Feb 09 2021 at 21:45)</a>:</h4>
<p>that said</p>



<a name="225762675"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762675" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762675">(Feb 09 2021 at 21:45)</a>:</h4>
<p>I don't know why you would actually WANT to say that</p>



<a name="225762681"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762681" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762681">(Feb 09 2021 at 21:45)</a>:</h4>
<p>which I guess is your point :)</p>



<a name="225762688"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762688" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762688">(Feb 09 2021 at 21:45)</a>:</h4>
<p>yeah</p>



<a name="225762701"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762701" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762701">(Feb 09 2021 at 21:45)</a>:</h4>
<p>it is certainly a valid thing to say</p>



<a name="225762754"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762754" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762754">(Feb 09 2021 at 21:46)</a>:</h4>
<p>but I agree it will be less common</p>



<a name="225762764"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762764" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762764">(Feb 09 2021 at 21:46)</a>:</h4>
<p>which is kind of what I'm concerned about</p>



<a name="225762783"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762783" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762783">(Feb 09 2021 at 21:46)</a>:</h4>
<p>that said, I am also concerned that just "randomly" deciding what is and is not binding points lke this</p>



<a name="225762788"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762788" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762788">(Feb 09 2021 at 21:46)</a>:</h4>
<p>is going to be very confusing</p>



<a name="225762803"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762803" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762803">(Feb 09 2021 at 21:46)</a>:</h4>
<p>which is why I casting about for an alternative model</p>



<a name="225762811"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762811" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762811">(Feb 09 2021 at 21:46)</a>:</h4>
<p>that could be more uniform</p>



<a name="225762876"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762876" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762876">(Feb 09 2021 at 21:47)</a>:</h4>
<p>I think I need to think more about this</p>



<a name="225762905"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762905" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762905">(Feb 09 2021 at 21:47)</a>:</h4>
<p>Like, a situation where asking <code>&lt;T as Foo&gt;::Bar&lt;'b&gt; == Baz&lt;'a&gt;</code></p>



<a name="225762909"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762909" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762909">(Feb 09 2021 at 21:47)</a>:</h4>
<p>is useful</p>



<a name="225762979"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762979" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762979">(Feb 09 2021 at 21:48)</a>:</h4>
<p>so</p>



<a name="225762993"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762993" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762993">(Feb 09 2021 at 21:48)</a>:</h4>
<p>the fact that you can't do specialization on lifetimes is relevant here BUT</p>



<a name="225762997"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225762997" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225762997">(Feb 09 2021 at 21:48)</a>:</h4>
<p>if we extend to <em>types</em></p>



<a name="225763002"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763002" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763002">(Feb 09 2021 at 21:48)</a>:</h4>
<p>well</p>



<a name="225763013"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763013" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763013">(Feb 09 2021 at 21:48)</a>:</h4>
<p>ok so I take that back :)</p>



<a name="225763023"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763023" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763023">(Feb 09 2021 at 21:48)</a>:</h4>
<p>we don't let you specialize inside of GATs</p>



<a name="225763117"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763117" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763117">(Feb 09 2021 at 21:49)</a>:</h4>
<p>My brain hurts</p>



<a name="225763226"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763226" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763226">(Feb 09 2021 at 21:50)</a>:</h4>
<p>I can't really come up with a reason you would not want a binder there</p>



<a name="225763229"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763229" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763229">(Feb 09 2021 at 21:50)</a>:</h4>
<p><span class="user-mention" data-user-id="116118">@Matthew Jasper</span> do you have an example?</p>



<a name="225763355"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763355" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763355">(Feb 09 2021 at 21:51)</a>:</h4>
<p>well this was an interesting conversation</p>



<a name="225763369"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763369" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763369">(Feb 09 2021 at 21:51)</a>:</h4>
<p>even if we went pretty deep :)</p>



<a name="225763458"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763458" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763458">(Feb 09 2021 at 21:52)</a>:</h4>
<p>Right so</p>



<a name="225763473"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763473" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763473">(Feb 09 2021 at 21:52)</a>:</h4>
<p>moving forward</p>



<a name="225763499"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763499" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763499">(Feb 09 2021 at 21:52)</a>:</h4>
<p>This seems pretty high priority</p>



<a name="225763526"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763526" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763526">(Feb 09 2021 at 21:53)</a>:</h4>
<p>I.e. decided on the syntax here</p>



<a name="225763583"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763583" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763583">(Feb 09 2021 at 21:53)</a>:</h4>
<p>yeah, particularly if we were to take aim at some of my more ambitious proposals</p>



<a name="225763651"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763651" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763651">(Feb 09 2021 at 21:54)</a>:</h4>
<p>I guess i wouldn't be <em>opposed</em> to landing -- and even stabilizing -- a <code>for</code>-based syntax</p>



<a name="225763684"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763684" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763684">(Feb 09 2021 at 21:54)</a>:</h4>
<p>i have to think about it</p>



<a name="225763691"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763691" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763691">(Feb 09 2021 at 21:54)</a>:</h4>
<p>I just wonder if that's a bit <em>too</em> ambitious?</p>



<a name="225763697"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763697" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763697">(Feb 09 2021 at 21:54)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116009">nikomatsakis</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225763583">said</a>:</p>
<blockquote>
<p>yeah, particularly if we were to take aim at some of my more ambitious proposals</p>
</blockquote>
<p>I'd prefer to separate this out as an ergonomic improvement</p>



<a name="225763702"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763702" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763702">(Feb 09 2021 at 21:54)</a>:</h4>
<p>that I can argue for on its own merits</p>



<a name="225763704"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763704" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763704">(Feb 09 2021 at 21:54)</a>:</h4>
<p>I don't want it to be a blocker</p>



<a name="225763731"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763731" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763731">(Feb 09 2021 at 21:54)</a>:</h4>
<p><span class="user-mention silent" data-user-id="232957">Jack Huey</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225763691">said</a>:</p>
<blockquote>
<p>I just wonder if that's a bit <em>too</em> ambitious?</p>
</blockquote>
<p>i think it is to have as a blocker on progress</p>



<a name="225763759"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763759" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763759">(Feb 09 2021 at 21:55)</a>:</h4>
<p>So, next question</p>



<a name="225763798"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763798" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763798">(Feb 09 2021 at 21:55)</a>:</h4>
<p>If we start with the <code>for&lt;'a&gt; T: Foo&lt;Bar&lt;'a&gt; = Baz&lt;'a&gt;&gt;</code> syntax</p>



<a name="225763820"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763820" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763820">(Feb 09 2021 at 21:55)</a>:</h4>
<p>can we later allow <code>T: Foo&lt;Bar&lt;'a&gt; = Baz&lt;'a&gt;&gt;</code></p>



<a name="225763851"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763851" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763851">(Feb 09 2021 at 21:55)</a>:</h4>
<p>would be similar to in-band lifetimes, yeah?</p>



<a name="225763913"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763913" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763913">(Feb 09 2021 at 21:56)</a>:</h4>
<p>so what's confusing to me <span class="user-mention" data-user-id="232957">@Jack Huey</span></p>



<a name="225763920"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763920" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763920">(Feb 09 2021 at 21:56)</a>:</h4>
<p>is that i don't think those two things would be equivalent, even with "implicit" binders</p>



<a name="225763942"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763942" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763942">(Feb 09 2021 at 21:56)</a>:</h4>
<p>well hmm</p>



<a name="225763953"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763953" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763953">(Feb 09 2021 at 21:56)</a>:</h4>
<p>I think I agree with you</p>



<a name="225763970"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763970" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763970">(Feb 09 2021 at 21:57)</a>:</h4>
<p>I'm wondering</p>



<a name="225763984"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225763984" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225763984">(Feb 09 2021 at 21:57)</a>:</h4>
<p>i may be incorrect</p>



<a name="225764030"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764030" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764030">(Feb 09 2021 at 21:57)</a>:</h4>
<p>it seems weird because you could write something lke</p>



<a name="225764083"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764083" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764083">(Feb 09 2021 at 21:57)</a>:</h4>
<p><code>for&lt;'a&gt; T: Foo&lt;Bar&lt;'a&gt; = ..., Baz&lt;'a&gt; = ...&gt;</code></p>



<a name="225764161"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764161" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764161">(Feb 09 2021 at 21:58)</a>:</h4>
<p>but I guess that just expands to </p>
<ul>
<li><code>for&lt;'a&gt; ProjectionEq(&lt;T as Foo&gt;::Bar&lt;'a&gt; = ...)</code></li>
<li><code>for&lt;'a&gt; ProjectionEq(&lt;T as Foo&gt;::Baz&lt;'a&gt; = ...)</code></li>
</ul>



<a name="225764165"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764165" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764165">(Feb 09 2021 at 21:58)</a>:</h4>
<p>yes</p>



<a name="225764173"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764173" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764173">(Feb 09 2021 at 21:58)</a>:</h4>
<p>so i think i am .. wrong</p>



<a name="225764182"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764182" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764182">(Feb 09 2021 at 21:58)</a>:</h4>
<p>I was about to say that</p>



<a name="225764197"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764197" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764197">(Feb 09 2021 at 21:58)</a>:</h4>
<p>it's counterintuitive to me, but actually that is a fine spot for the binder</p>



<a name="225764230"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764230" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764230">(Feb 09 2021 at 21:59)</a>:</h4>
<p>you could of course also have <code>for&lt;'a&gt; T: Foo&lt;'a, Bar&lt;'a&gt; = ...&gt;</code></p>



<a name="225764264"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764264" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764264">(Feb 09 2021 at 21:59)</a>:</h4>
<p>this is where the 'can you just drop the binder' question comes in</p>



<a name="225764291"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764291" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> detrumi <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764291">(Feb 09 2021 at 21:59)</a>:</h4>
<p>Ah, so it's not always directly to the left of the <code>=</code>. I was wondering about that</p>



<a name="225764294"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764294" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764294">(Feb 09 2021 at 21:59)</a>:</h4>
<p>but that expands to <code>for&lt;'a&gt; T: Foo&lt;'a&gt;</code> and <code>for&lt;'a&gt; &lt;T as Foo&lt;'a&gt;&gt;::Bar&lt;'a&gt; = ...</code></p>



<a name="225764304"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764304" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764304">(Feb 09 2021 at 21:59)</a>:</h4>
<p>right</p>



<a name="225764384"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764384" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764384">(Feb 09 2021 at 22:00)</a>:</h4>
<p>oh no, flashbacks to binder refactor</p>



<a name="225764420"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764420" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764420">(Feb 09 2021 at 22:00)</a>:</h4>
<p>Anyways, that was a quick hour</p>



<a name="225764462"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764462" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764462">(Feb 09 2021 at 22:00)</a>:</h4>
<p>so -- if you had "implied" binders, would <code>T: Foo&lt;'a, Bar&lt;'a&gt; = ..&gt;</code> mean:</p>
<ul>
<li><code>for&lt;'a&gt; { ProjectionEq(&lt;T as Foo&lt;'a&gt;&gt;::Bar&lt;'a&gt; = ...)</code></li>
</ul>
<p>or</p>
<ul>
<li><code>for&lt;'a, 'b&gt; { ProjectionEq(&lt;T as Foo&lt;'a&gt;&gt;::Bar&lt;'b&gt; = ...)</code></li>
</ul>



<a name="225764476"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764476" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764476">(Feb 09 2021 at 22:00)</a>:</h4>
<p>this is the usual problem with "in-band lifetimes'</p>



<a name="225764480"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764480" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764480">(Feb 09 2021 at 22:01)</a>:</h4>
<p>how to decide when two uses of <code>'a</code> are meant to be "the same"</p>



<a name="225764484"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764484" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764484">(Feb 09 2021 at 22:01)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116009">nikomatsakis</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225763226">said</a>:</p>
<blockquote>
<p>I can't really come up with a reason you would not want a binder there</p>
</blockquote>
<p>Can we think about this bit? (async) This would be helpful to me</p>



<a name="225764491"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764491" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764491">(Feb 09 2021 at 22:01)</a>:</h4>
<p>or "different'</p>



<a name="225764507"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764507" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764507">(Feb 09 2021 at 22:01)</a>:</h4>
<p>yes, we can</p>



<a name="225764541"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764541" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764541">(Feb 09 2021 at 22:01)</a>:</h4>
<p>Well, I haven't looked at the in-band lifetime proposal</p>



<a name="225764564"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764564" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764564">(Feb 09 2021 at 22:01)</a>:</h4>
<p>But I assumed that anytime you mention <code>'a</code>, you mean the same <code>'a</code></p>



<a name="225764573"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764573" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764573">(Feb 09 2021 at 22:01)</a>:</h4>
<p>obviously it didn't address this issue</p>



<a name="225764617"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764617" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764617">(Feb 09 2021 at 22:02)</a>:</h4>
<p>I'm not a fan of the in-band lifetime proposal anymore, tbh</p>



<a name="225764631"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764631" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764631">(Feb 09 2021 at 22:02)</a>:</h4>
<p>not because it's not nice to use</p>



<a name="225764632"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764632" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764632">(Feb 09 2021 at 22:02)</a>:</h4>
<p>Welp</p>



<a name="225764661"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764661" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764661">(Feb 09 2021 at 22:02)</a>:</h4>
<p>but because I would prefer something more ambitious :) and more clear, I hope</p>



<a name="225764678"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764678" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764678">(Feb 09 2021 at 22:02)</a>:</h4>
<p><em>anyway</em></p>



<a name="225764694"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764694" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764694">(Feb 09 2021 at 22:02)</a>:</h4>
<p>Well, that sounds like something to think about too :)</p>



<a name="225764695"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764695" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764695">(Feb 09 2021 at 22:02)</a>:</h4>
<p>i think if I were going to pick a path</p>



<a name="225764700"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764700" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764700">(Feb 09 2021 at 22:02)</a>:</h4>
<p>I would say "require <code>for</code>"</p>



<a name="225764715"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764715" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764715">(Feb 09 2021 at 22:03)</a>:</h4>
<p>The example where you want to use an externally defined lifetime is this one: <a href="https://github.com/rust-lang/rust/issues/70303">https://github.com/rust-lang/rust/issues/70303</a> if you fix the bound to <code>Doc: Document&lt;Cursor&lt;'d&gt; = Cursor&gt;</code> everything works, but using a binder doesn't work. Admittedly this code doesn't make much sense.</p>



<a name="225764716"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764716" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764716">(Feb 09 2021 at 22:03)</a>:</h4>
<p>and let me make the case for my more ambitious design</p>



<a name="225764867"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764867" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764867">(Feb 09 2021 at 22:04)</a>:</h4>
<div class="codehilite"><pre><span></span><code>    Doc: Document&lt;Cursor = Cursor&gt;,
</code></pre></div>



<a name="225764875"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764875" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764875">(Feb 09 2021 at 22:04)</a>:</h4>
<p>that bound?</p>



<a name="225764886"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764886" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764886">(Feb 09 2021 at 22:04)</a>:</h4>
<p>That one</p>



<a name="225764914"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764914" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764914">(Feb 09 2021 at 22:04)</a>:</h4>
<p>why doesn't a binder work</p>



<a name="225764924"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764924" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764924">(Feb 09 2021 at 22:04)</a>:</h4>
<p>The fact that there is a param named <code>Cursor</code> but the associated type is also named <code>Cursor</code> is scary</p>



<a name="225764933"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764933" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764933">(Feb 09 2021 at 22:04)</a>:</h4>
<p>and confusing</p>



<a name="225764974"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764974" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764974">(Feb 09 2021 at 22:05)</a>:</h4>
<p>ok</p>



<a name="225764977"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764977" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764977">(Feb 09 2021 at 22:05)</a>:</h4>
<p><code>Cursor</code> (the type param) references <code>'d</code> at the call site.</p>



<a name="225764999"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225764999" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225764999">(Feb 09 2021 at 22:05)</a>:</h4>
<p>yeah ok</p>



<a name="225765025"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765025" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765025">(Feb 09 2021 at 22:05)</a>:</h4>
<p>the generic type parameter is key there</p>



<a name="225765036"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765036" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765036">(Feb 09 2021 at 22:06)</a>:</h4>
<p>that's what I was missing</p>



<a name="225765098"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765098" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765098">(Feb 09 2021 at 22:06)</a>:</h4>
<p>if we had full "HKT"</p>



<a name="225765126"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765126" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765126">(Feb 09 2021 at 22:06)</a>:</h4>
<p>Cursor could have kind <code>(lifetime -&gt; type)</code></p>



<a name="225765161"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765161" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765161">(Feb 09 2021 at 22:06)</a>:</h4>
<p>Well, I have some reading/thinking to do</p>



<a name="225765193"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765193" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765193">(Feb 09 2021 at 22:07)</a>:</h4>
<p>but because we don't, you only get the type for some <em>particular</em> lifetime</p>



<a name="225765232"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765232" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765232">(Feb 09 2021 at 22:07)</a>:</h4>
<p>and so you want to be able to say that</p>



<a name="225765237"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765237" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765237">(Feb 09 2021 at 22:07)</a>:</h4>
<p>ok, makes sense</p>



<a name="225765250"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765250" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765250">(Feb 09 2021 at 22:07)</a>:</h4>
<p>seems obvious now :)</p>



<a name="225765256"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765256" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765256">(Feb 09 2021 at 22:07)</a>:</h4>
<p><span class="user-mention silent" data-user-id="232957">Jack Huey</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225765161">said</a>:</p>
<blockquote>
<p>Well, I have some reading/thinking to do</p>
</blockquote>
<p>about kinds? :)</p>



<a name="225765332"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765332" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765332">(Feb 09 2021 at 22:08)</a>:</h4>
<p>just I think my understanding of GATs isn't quite complete</p>



<a name="225765391"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765391" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765391">(Feb 09 2021 at 22:09)</a>:</h4>
<p>Can I be added to that hack md group?</p>



<a name="225765407"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765407" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765407">(Feb 09 2021 at 22:09)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116009">nikomatsakis</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225764700">said</a>:</p>
<blockquote>
<p>I would say "require <code>for</code>"</p>
</blockquote>
<p>well I think this is the conclusion</p>



<a name="225765544"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765544" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765544">(Feb 09 2021 at 22:10)</a>:</h4>
<p>Okay so current implemented syntax?</p>



<a name="225765549"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765549" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765549">(Feb 09 2021 at 22:10)</a>:</h4>
<p>yes</p>



<a name="225765564"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765564" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765564">(Feb 09 2021 at 22:10)</a>:</h4>
<p>great, makes it easy</p>



<a name="225765569"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765569" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765569">(Feb 09 2021 at 22:10)</a>:</h4>
<p>I still think we should change it, I just think that comes in the "make things nice to use" part of the skill tree</p>



<a name="225765578"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765578" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765578">(Feb 09 2021 at 22:10)</a>:</h4>
<p>the thing I like about the skill tree is orienting around goals</p>



<a name="225765585"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765585" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765585">(Feb 09 2021 at 22:10)</a>:</h4>
<p>I am going to put in a bit of thought into what I mean</p>



<a name="225765596"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765596" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Jack Huey <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765596">(Feb 09 2021 at 22:11)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116118">Matthew Jasper</span> <a href="#narrow/stream/144729-wg-traits/topic/meeting.202021-02-09/near/225765391">said</a>:</p>
<blockquote>
<p>Can I be added to that hack md group?</p>
</blockquote>
<p>added</p>



<a name="225765610"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765610" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765610">(Feb 09 2021 at 22:11)</a>:</h4>
<p>whoops, sorry, missed that <span class="user-mention" data-user-id="116118">@Matthew Jasper</span></p>



<a name="225765753"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/225765753" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Matthew Jasper <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#225765753">(Feb 09 2021 at 22:12)</a>:</h4>
<p>Thanks</p>



<a name="226141115"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/144729-wg-traits/topic/meeting%202021-02-09/near/226141115" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Zahari Dichev <a href="https://rust-lang.github.io/zulip_archive/stream/144729-wg-traits/topic/meeting.202021-02-09.html#226141115">(Feb 12 2021 at 14:13)</a>:</h4>
<p>(deleted)</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
</html>